Combined effect of meat composition and heating parameters on the physicochemical state of proteins

International audience; During meat cooking, proteins undergo some oxidations and conformation changes which can induce a loss in the nutritional value of products. The objective of this study was to determine the effect of heat treatments on the physicochemical state of proteins (oxidation and thermal denaturation). A great number of experiments were performed on mimetic models. Two mimetic models were used: a basic model, composed of an aqueous suspension of myofibrillar proteins, and a complex model, in which oxidants were added in physiological concentrations. Heat treatments were applied on the two models at 45°C, 60°C, 75°C and 90°C during 5, 10, 30, 60 and 120 min. Then, the results were compared to those obtained on a pork meat model (M. Longissimus dorsi), cooked in the same conditions. In these three models, myofibrillar proteins were the target of the treatments. Protein oxidation was assessed by the carbonyl groups and thermal denaturation was evaluated by the measurement of protein surface hydrophobicity. The mimetic models showed that carbonyls can not be produced under the thermal process alone; oxidants are required for their formation. A synergic effect of the oxidants and heat treatments was noticed on protein oxidation. Carbonyl production was considerably higher in the complex mimetic model than in meat. On the contrary, changes in protein hydrophobicity were dominated by the thermal process and hydrophobicity values were higher in meat than in the mimetic model.